1. Field of the Invention
The present invention relates to a sensor system for a locking system as well as to a method for detecting tampering at a locking system, in particular in locking systems of doors or gates, for example, at entrance doors to buildings or apartment doors situated within buildings.
2. Description of the Related Art
The term “lock picking” refers to the damage-free opening of cylinder locks of a lock with the aid of a specifically adapted break-in tool. The possibility of opening a lock at all by lock picking essentially results from inaccuracies during manufacturing of cylinder locks which are mechanically either unpreventable or preventable only at high costs. For this reason, locking systems including cylinder pins have pin openings which are offset from one another. During lock picking, the cylinder lock may be subjected to pretension in such a way that only one of the pins is clamped. By correspondingly sensitive displacement, this pin may subsequently be brought into an unlocked position. Once the unlocked position is reached, the cylinder core may be rotated further by the minimal offset so that the next pin may be subjected to pretension. Using this iterative process, the cylinder core may be unlocked without a key being required and without the lock being damaged.
This break-in method is particularly unpleasant for victims, since providing proof of an unauthorized entry is either impossible or possible only with an examination by an expert.
Different approaches for proving break-in attempts by lock picking are known from the related art. U.S. Pat. No. 5,567,099 A describes a system which is able to detect a break-in using motion detection with the aid of light sensors and trigger an alarm. U.S. Pat. No. 6,963,281 A describes a system including multiple magnetic contact switches which are disconnected during a break-in attempt so that an alarm may accordingly be triggered. U.S. Pat. No. 3,475,934 A and U.S. Pat. No. 6,854,307 A each describe additional inserts into a key hole which may thereby be locked. U.S. Pat. No. 4,186,578 A describes a detection method with which the insertion of electrically conductive material into a key hole may be detected. Published European patent application document EP 1 981 010 A2 describes a system which may detect a break-in by measuring energy during the break-in attempt and comparing the measured energy to a stored energy signature. Finally, U.S. Pat. No. 7,397,341 A1 describes a combination of an acoustic sensor and a vibration sensor, whose detected signals are compared to reference signals in order to detect the signature of a lock-picking attack.
However, there is a need for approaches for the detection of break-in attempts, in particular by lock picking, which may differentiate more reliably and dependably between actual break-in attempts and other activities in the door area or justified locking attempts taking more time.